Power circuit for electric ranges



Jan. 12, 1937. D F|NDLAY 2,067,481

POWER CIRCUIT FOR ELECTRIC RANGES Filed Nov. 19, 1934 BROIL PREHEAT IPOSITION "PREHEAT' "BAKE" 5 POSITION v INVENTOR= a 2 D UGLAS 0. FIN AV xI I I F1 g3 trolled circuit breake Patented Jan. 12, 1937 POWER CIRCUITFOR ELECTRIC RANGES Douglas David Findlay, Carleton Place, Ontario,Canada Application November 19, 1934,

Serial No. 15355955 for electric ranges and more particularly to theelectric circuits for controlling the flow of current 'to the heatingelements. 5' In ovens of this character it is common practice to.provide two heating elements, a top element and a bottom element,sometimes with a switch controlling the power supply to both elementsand a single-pole thermostatically conin the baking element circuit, butmore ge erally with two switches, one for each heating element and adouble-pole thermostatically controlled circuit breaker which interruptsthe power supply to each switch. The latter arrangement 'is cumbersomeand expensive while the former is only partially automatic.

Sometimes, in order to control both oven elements with a single polecircuit breaker, both elements are red from the same controlled leg ofthe 3-wire supply in parallel. This arrangement causes an undesirablevoltage drop, resulting in slower action in the preheating position, andcreates an unbalanced load, which is objectionable. A pilot light issometimes provided to indicate when the elements are energized. Suchcircuit arrangements have not provided for most efllcient and rapidpreheating of the oven, nor do they provide for single manual control ofthe power load circuit whereby both heating elements may be connected inseries with high voltage current supply or either element separatelywith low.,voltage current supply.

An object of the present invention is to provide an improved circuitincluding a single-pole thermostatic circuit breaker and pilot lightwith uni-'- tary manualcontrol, so that both heating elements may beheated in series at high voltage and either of the elements may beheated separately at low voltage. A further object is to provide acircuit arrangement in which a relatively inexpensive single-polethermostatic circuit breaker and pilot light are incorporated in all oi.a plurality of the oven heating circuits con-, trolled by a manuallyoperated switch, andin which the lower voltage power supply is providedfor each heating element through the leg of the power supply circuitwhich contains the thermostatic circuit breaker. Another object is topro vide an improved dial arrangement for setting the temperature atwhich the thermostatic circuit breaker automatically breaks the powersupplycircuit feeding the heating elements. Y

The invention will now be described with reference to the accompanyingdrawing, in which Figure 1 represents the electric circuit;

vstrated in Figure 3.

. 3 Claims. 01. 219-40) This invention relates to oven heat controlFigure 2 is a front view of an'electric range, partially broken away;

Figure 3 represents the three difierent connections of the heatingelements in the circuit; and

' Figure 4 illustrates an arrangement of. the dial 5 'oi thethermostatic control on the panel.

' In the drawing, I represents the top and 2 the. bottom heating elementfor the oven illustrated in Figure 2. 3 is a multi-way switch, operablefrom the switch panel 4; 5 a single-pole .thermo- 10 staticallycontrolled circuit breaker, of well known construction, having a controldial 6 on the switch panel, and 1 represents fused cutouts for the powersupply which is connected to the terminal block 8 for reception of 220volt current 5 or volt current, depending upon the position v of theswitch 3. A pilot light 9 is connected with the circuit breaker 5 andthe common line terminal l3. c

The heating elements I and 2 are connected in series and to the switch 3with wires l0 and. II, while a common wire l2 also contacts with theswitch at a point IS. The power line H connects one fused cutout withthe switch, while the other power line l5 passes through the circuitbreaker 5 to the switch and the neutral line It leads directly from theterminal block to the switch.

The dial for setting the temperature at which the thermostatic circuitbreaker operates to interrupt the current flow is arranged in an openingin the panel 6', as illustrated more or. less diagrammatically inFigures 2 and 4. The dial may take the form of an open ended cylinder I!mounted for rotation on ashait l8 and having a transparent well illcarrying a desired temperature scale. An index pointer 20 is provided onthe outturned lip of the panel opening. The dial may be provided withknurls 2| to afford gripping contact for rotating the dial. The pilot tolight 9 is locatedwithin the cylinder to illuminate the temperaturescale and, at the same time, indicate if the power is on or oil.Alternatively, if desired, the pilot lamp may be arranged behind awindow in the panel in a known manner. The three operating positions ofthe circuit with respect to the two heating elements, as controlled bythe switch, are diagrammatically illu- In the preheating or 1 position,when it is'desired to raise the tempera- 50 ture of the oven quickly,both elements are energized in series by the 220 volt current supply ofthe two power lines It and I5, the neutral wire being broken asindicated. at X. With the switch in the 2 position Bake or 3 position 55Q "Broil", the same power circuit energizes the heating element l or 2as required with 110 volt current sup ly of one power line l5 andutilization of the neutral wire I6, the other power line ll being brokenas indicated at X in each case. The thermostat control and pilot lightare, as shown, in the energized circuit in all positions. The operatingpositions of the circuit may be -described with respect to Figure 1 asfollows: (1) line I! through switch to wire I, element I, element 2,wire ll through switch to line ll; (2) line l6 through switch to wire H,element 2, wire I! through switch to neutral line It; (3)

line I5 through switch to wire Iii, element 1, wire l2 through switch toneutral line It. The utilization of power line IS in all operatingpositions permits control of the circuit at all times by means of thesingle-pole circuit breaker 5 in the line IS. The pilot light 9 byconnection to the circuit breaker and to wire i2 at terminal l3 of theswitch is also in the energized circuit at all times.

It will be observed that this circuit arrangement aflords simplicity ofoperation by a single manual switch control of all heating positions oithe elements, while in all such positions the circuit is automaticallycontrolled by the singlepole thermostatic circuit breaker, with thepilot light burning when the power is on. With the switch in No. 1position, the two heating elements are connected in series across thehigh voltage line, giving maximum heating eflect in the oven, while inpositions No. 2 and No. 3 of theswitch the baking and broiling circuits,respectively, are energized. The pilot light is always in circuit withthe automatic control and thus when the automatic control breaks thecircuit the light goes out, indicating that the desired oven temperaturehas been reached. This automatically indicates the time at which theswitch 3 should be manually shifted. It will be appreciated that thisarrangement greatly facilitates minimum power consumption as well asmaintenance oi best temperature conditions in the oven.

with this circuit arrangement a single-pole, relatively inexpensivecircuit breaker adequately provides for thermostatically breakingwhichever power circuit may be in operation. The switch 3 may be 01 anydesired construction to operate as shown.

I! desired, the pilot light may be arranged to come on when thetemperature, for which the thermostatic circuit breaker is set, has beenreached. In this case the pilot light is connected across the bindingposts of the circuit breaker 5.

A clock maybe inserted in the power load circuit between the circuitbreaker and the terminal block to close and break the circuitautomatically at fixed times.

The circuit is adapted for any desired power voltages and the highervoltage may. be double the lower voltage or the square root of threetimes the lower voltage, as is sometimes the case.

I claim:

1. An electric circuit for the oven of cooking ranges comprising twoheating elements, a power supply circuit for said elements including twoenergized wires and a neutral wire, and control means for said circuitcomprising a switch, said energized wires and the neutral wire beingconnected to terminals in the switch, connecting wires leading fromterminals in the switch to each of said elements and a third common wireleading from a terminal in the switch and connected to both of saidelements, the switch in one operating position being arranged to connectthe terminals of said energized wires to the terminals of saidconnecting wires with the terminals of the neutral wire and the commonwire disconnected, and in other operating positions to connect theterminal of the same one oi the energized wires to either of theterminals of the connecting wires and the terminalof the neutral wirewith the terminal 01' said common wire, whereby one of said energizedwires is commonly utilized in all operating positions. oi said circuit.

2. A circuit as defined in claim 1 wherein a single-polethermostatically controlled circuit breaker is interposed in saidcommonly utilized wire and arranged to open and close said circuit whenthe temperature in the oven reaches predetermined limits.

3. A circuit as defined in claim 1 wherein a single-polethermostatically controlled circuit breaker is interposed in saidcommonly utilized wire and arranged to open and close said circuit whenthe temperature in the oven reaches predetermined limits, and wherein apilot light is connected between the circuit breaker and said commonwire terminal of said switch whereby

